Disposable absorbent articles

ABSTRACT

A disposable absorbent article, such as a diaper, an incontinence guard or the like, includes an inner, liquid-permeable casing sheet, which when the article is worn lies nearest the body of the wearer, an outer, liquid-impermeable casing sheet, an absorbent pad enclosed between the two casing sheets, and a layer of fibre wadding disposed between the absorbent pad and the inner casing sheet. The inner casing sheet is joined to the absorbent pad along two longitudinal lines forming permanent fold lines which divide the article, over at least a part thereof, into a central elongated part and two edge-parts located symmetrically on respective sides of the central elongated part. Each edge-part is folded between the respective fold line and its lateral edge such as to form an inwardly upstanding longitudinal fold in the outer casing sheet. The article has mutually opposed portions in the longitudinal folds, which portions are permanently joined to each other, whereby the edge-parts form inwardly upstanding embankment walls.

The present invention relates to a disposable absorbent article, such asa diaper, an incontinence guard or like article, which comprises aliquid-permeable casing layer, which when the article is worn liesnearest to the wearer's body, a liquid-impermeable casing sheet orbacking sheet, and an absorbent pad enclosed between the two casingsheets.

Disposable absorbent articles, such as children's diapers or diaperswhich are intended for use as incontinence guards by adults, arenormally constructed of a nonwoven layer through which the urineexcreted passes, an absorbent layer of, for instance, cellulose fluff,optionally combined with so-called superabsorbents, and aliquid-impervious layer of polyethylene, for instance. For reasons of aprocess-technical nature, such articles have most often a flat,rectangular configuration, although such product configurations are notpreferable in view of the fact that the body contours of the user areanything but flat.

In order to avoid lateral leakage through the sides of the article whenworn, it is important that the article does not become folded orwrinkled so that liquid is able to run out through the sides of thearticle. The problem associated with the formation of folds and wrinklesis, naturally, pronounced when the wearer walks, sits down or moves inany other way, since the thighs of the wearer subject the article toexternal pressures sufficiently great to deform markedly the absorbentpad incorporated in the article, mainly in its transverse direction. Itis thus important to configure the article such that the crotch regionthereof will be relatively narrow. By crotch region is meant that regionof the article which is intended to be located between the user's thighswhen the article is worn. Since it is precisely the crotch region of thearticle which is responsible for receiving the largest amount of liquidexcreted, it is extremely important that this crotch region, despitebeing narrow, is able to collect and absorb the liquid rapidly andeffectively, while obtaining a good lateral seal at the same time.

The problem of lateral leakage cannot be solved solely by so shaping thearticle in manufacture that its crotch region will be narrower than itsfront and rear end respectively, since even in this case the article hasa flat configuration and is consequently still wrinkled or folded in thecrotch region when the absorbent pad is folded along the body of theperson wearing the article. Although the liquid-permeable outermaterials, essentially nonwoven materials, commercially available atpresent and used in sanitary products of the type diapers andincontinence guards, will allow a certain amount of liquid to passrapidly therethrough, when the liquid is excreted quickly in largequantities, as is particularly the case with adult incontinence, part ofthis liquid will remain on top of the surface material and is therewithable to leak through any folds or wrinkles located between the absorbentpad and the user's body. This is because the absorbent material usedpredominently in present day absorbent products, namely cellulose fluff,comprises fibres which are so fine that the cavities therebetween becomequickly filled locally with liquid, with the result that liquid whichremains unabsorbed cannot be absorbed by the material immediately butmust remain on top of the surface material.

A sanitary product must also be able to receive and retain a largequantity of liquid while subjected to external forces, both during thetime taken for the liquid to penetrate the liquid-permeable outermaterial and subsequent to the liquid having been absorbed by theabsorbent pad.

When manufacturing such articles, it is known to fold the outer,elongated parts of an initially flat and rectangular diaper in towardsthe central elongated part thereof. The intention is to obtain a crotchregion which is narrower than the ends of the diaper. Such diapers arereferred to generally as wing-folded diapers and an example of one suchdiaper is described and illustrated in the U.S. Pat. No. 3,875,943.However, despite all, a wing-folded diaper is to be considered flat andcan thus still be folded or wrinkled in the diaper crotch region, whichcan extend out as far as the side edges of the diaper and therewithcause leakage. Another drawback with wing-folded diapers is that it isnecessary for the user to extend the inwardly folded side-parts at thediaper ends when wishing to use the diaper, which naturally complicateshandling of the product.

Diapers which are cut to provide crotch regions narrower than the diaperend-parts are known, e.g., from U.S. Pat. No. 2,627,858. Such diapersare referred to generally as hour-glass diapers. Other diaperconfigurations include the T-configuration known, for instance, fromU.S. Pat. No. 3,768,479. All of these diaper configurations areconcerned with the body configuration of the wearer in the crotchregion, but nevertheless present a flat shape and, similarly to thewing-folded diapers, are therewith poorly adapted to the shape of thewearer's body in general and the flat absorbent body is liable to befolded or wrinkled in its transverse direction when folded upwardsaround the body of the wearer.

U.S. Pat. No. 4,685,914 describes another embodiment of a diaper orincontinence guard in which an absorbent pad or body is applied in theform of a boat-shaped foamed-polyethylene shell. The use of a separateouter basin as a liquid-impervious casing is both expensive andcomplicated, however.

The U.S. Pat. No. 4,655,759 teaches a method of providing sanitarytowels with embossed channels along which the longitudinally extendingedge-parts of the towel can be folded-up to form a kind of container,therewith reducing the risk of leakage.

However, the fact is that wrinkling or folding of the sanitary toweloccurs solely as a result of the pressure exerted by the wearer's thighsagainst the towel in its transverse direction. Consequently, it is moreor less by chance that a truly leakage-proof region can be formedbetween the embossed channels. The edge-parts of the towel can, inprinciple, be curved or likewise deformed in any manner whatsoever whensubjected to the force of the wearer's thighs and consequently there isno guarantee whatsoever that a leakage-proof region will be obtained. Incomparison with an incontinence guard and a diaper, a sanitary towel isintended to absorb much less liquid and is subjected to much smallerliquid flows.

The present invention relates to the provision of absorbent articlessuch as diapers, or incontinence guards, which are anatomicallyconfigured, which have a large liquid-collecting capacity both beforeand after absorption, which can absorb liquid rapidly, and which can beproduced continuously at high production speeds and at low cost, withthe aid of simple production means and without appreciable materialwastage.

An inventive absorbent product is characterized mainly by at least twofold lines which extend permanently in the longitudinal direction of thearticle and which divide the article, over at least a part thereof, intoa central longitudinally extending part and edge-parts locatedsymmetrically on respective sides of said central part.

With the aid of simple manufacturing methods, the invention enables aproduct to be produced which presents a desired three-dimensionalstructure, starting from a flat blank comprising all materialsincorporated in an absorbent article. Thus, it is not necessary tomanufacture a separate, injection-moulded foamed-plastic shell, suchmanufacture requiring a plurality of additional process stages andrendering manufacture more expensive and more difficult to carry out.

Furthermore, upward-folding of the edge-parts results in the formationof liquid-enclosing embankments along the fold lines, these embankmentsforming, at the same time, the main contact surface of the article withthe body of the user in that region of the article in which the foldlines are located, such as to enable a large quantity of liquid excretedat one and the same time to be collected in an elongated, dammed centralpart of the inventive article.

The liquid is, in this way, held removed from the user at the same timeas the dammed, central part of the article provides an effective barrieragainst leakage of liquid still not absorbed.

There are primarily two properties which are important to an absorbentarticle, namely that the article is able to absorb large quantities ofliquid secreted momentarily, without liquid running over the edges ofthe article, and that the article will present a dry surface to thewearer subsequent to absorption. An article constructed in accordancewith the invention contains both of these properties, in addition toseveral other properties desirable in the case of an absorbent article,such as comfort and discretion in wear.

An absorbent article constructed in accordance with the presentinvention will now be described in more detail with reference to anexemplifying embodiment thereof illustrated in the accompanyingdrawings.

FIG. 1 is a view of an inventive absorbent article taken from above,with the side of the article intended to face towards the wearer facingtowards the viewer.

FIG. 2 is a sectional view of the absorbent article illustrated in FIG.1, taken on the line II--II of said Figure.

FIG. 3 is a view of a further embodiment of an inventive article takenfrom above, with the side of the article intended to face the wearerfacing towards the viewer.

FIG. 1 illustrates an absorbent article 1. The article 1 comprises aliquid-permeable sheet 2, made of a nonwoven fibre material, attached assurface material nearest the body of the wearer.

The sheet 2 is joined with an underlying absorbent pad by means of two,longitudinally extending sinusoidal fold lines 3, e.g. weld joins oradhesive joins, said fold lines 3 functioning to divide the article 1into a central part 6 and two edge-parts 7, 8. The parts 6, 7 and 8 arerelatively elongated, i.e. their extension in the longitudinal directionof the article is greater than their extension in the transversedirection thereof. As will be seen from the Figure, the back and frontend-parts 9, 10 are of mutually identical configuration and are providedwith a plurality of discrete joins 4 and joins 5 which end-seal theend-parts 9, 10. The joins 4, 5 may be seam welds or adhesive bonds, forinstance.

When the fold lines are formed by seam welds, the seams can be producedby any conventional welding technique whatsoever, e.g. by ultrasonicwelding, impulse welding or high frequency welding.

The illustrated fold lines 3, are not restricted to the sinusoidal curvepattern illustrated in FIG. 1, but may be linear or arcuate inconfiguration. Preferably, two fold lines 3 are provided, although it isalso conceivable to provide solely one fold line or a number of foldlines greater than three.

According to one embodiment of the invention (not shown) in order toincrease the flexibility of the article, the fold lines may be formed bytwo punctiform seams disposed along a continuous curve and forming apattern similar to that formed by the fold lines in FIG. 1, or any otherdesired pattern whatsoever. Neither is the scope of the inventionrestricted by the lengths of said fold lines. However, the fold linesshall be positioned so that the liquid-receiving part of the article,the so-called wetting location, is framed by the edge-parts 7, 8 andtherewith constitutes a region of the central part 6. It should bementioned in this connection that the distance between the fold lines 3may have any desired value and does not therefore limit the scope of theinvention.

The seams or joins 4 in respective end-parts 9, 10 may be smaller orgreater than three in number and may also be excluded totally. Similarto the fold lines 3, the seams 4 may have the form of discretepunctiform weld-bonds or may comprise continuous, curved seams where theshape of the curve is optional. The seams 4 result in a smaller articlecontact-surface with the body of the wearer, therewith enhancing thecomfort of the article when worn.

FIG. 2 illustrates an example of upward-folding of the edge-parts 7, 8in accordance with the invention. The expression "upward-folding" asused here includes all manner of folding or bending of the edge-partswhich will cause the edge-parts located externally of the fold-lines,when viewed as a whole, to form upstanding embankments or like walls inrelation to the central part, seen in a direction towards the wearer.For instance, as illustrated in FIG. 2, the edge-part can be foldeddouble in its longitudinal direction, wherewith the outer longitudinallyextending part will be folded in a direction away from the wearer.Appropriate fixation of the fold will result in a reduction in thetransverse extension of the edge-parts, causing an increase in thevertical extension or height extension of said edge-parts, such that theedge-parts form upstanding embankment walls.

Located immediately beneath the liquid-permeable sheet 2 is fibrewadding body 11. This wadding functions to receive the liquid excretedand to permit the liquid to pass rapidly therethrough. The wadding ispreferably loosely packed and is resilient in both its dry and its wetstate. The fibre wadding 11 may comprise, for instance, thermoplastic,weldable fibres, such as polyester, polypropylene or polyethylene fibresor mixtures thereof. So-called bicomponent fibres are suitable materialsin this regard, by which is meant fibres which comprise two kinds ofpolymer, for instance polypropylene/polyethylene, polyester/polyester orpolyester/polyethylene. The fibre wadding 11 may be either a woven ornon-woven structure, without departing from the inventive concept. Heatand binding agents are examples of the means by which a fibre waddingstructure can be bound. The adhesive bonding agent may, for instance, belatex. The wadding may also be hydrophobic or hydrophilic. It will beunderstood that natural fibres which exhibit the aforesaid propertiescan also be used.

An absorbent pad 12 located beneath the wadding comprises two layers ofsuperabsorbent material 13, 14 which is placed in powder form between aplurality of tissue layers 15. The superabsorbent material may have aform other than powder, e.g. may have the form of fibres. Bysuperabsorbent material is meant a material which can absorb a liquidquantity corresponding to several times its own weight. Thesuperabsorbents in respective layers differ essentially with regard toabsorption properties, absorption rates and liquid-retention abilitieswhen subjected to pressure. The superabsorbent in layer 14 has a veryhigh absorption rate, whereas the superabsorbent in layer 13 has a verypronounced ability to retain liquid when subjected to pressure. Each ofthe tissue layers 15 may comprise one or more layers of tissue. It isalso conceivable to use other types of carrier material than tissue, forinstance nonwoven material.

Placed beneath the absorbent pad 12 and between said pad and theliquid-permeable sheet 2 extending peripherally around the whole of thearticle is a liquid-impermeable sheet 16 made, for instance, ofpolyethylene or polypropylene. The liquid-permeable sheet 2 is joined tothe liquid-impermeable sheet 16, e.g., with the aid of an adhesivebinder, whereas the fibre wadding 11 is neither connected to theliquid-permeable sheet 2 nor to the liquid-impermeable sheet 16, withthe exception of the seam or join locations 3, 4 and 5. Theliquid-impermeable sheet 16 extends upwards to some extent along theupwardly raised edge-part 7, 8 which provides additional protectionagainst leakage from the sides of the article. The layer 16 extendsaround the margins of the end-parts 9, 10 and slightly inwardly thereof,as indicated by a broken line 17 in FIG. 1.

The edge-parts 7, 8 are joined in a double-fold, by means of a bondingmeans 20, for instance by means of an adhesive binding agent or apunctiform weld, a region 21, 22 of the liquid-permeable sheet 2 beingjoined with another region 23, 24 of said sheet within the samerespective edge-parts 7, 8 on the side surface of the article 1 facingaway from the user, i.e. the underside 25 of said article The bindingagent is, for instance, applied in the form of one or more glue points.The punctiform weld-joins may be one or more in number.

When the edge-parts 7, 8 are folded in this manner and fixated to theunderside 25 of the article, the edge-parts 7, 8 of the article impartto the central part of said article, as seen in its cross-direction, aconvex shape, at the same time as said edge-parts 7, 8 are erected to araised position in relation to the central part 6 as seen in the heightextension of the article. When the article is in use, the wearer'sthighs will press the edge-parts 7, 8 towards the central part 6, butbecause the edge-parts 7, 8 in their upwardly raised positions curveinwardly towards the central part 6, the occurring pressure forces willaccentuate still further the damming effect of the central part 6 andcounteract the tendency of the edge-parts 7, 8 to gape. Thus, inaccordance with the present invention, the apparently disadvantageousfact that the thighs of the wearer will deform the article in itstransverse direction is utilized in a beneficial manner to provide aconsiderably improved absorbent product or article, both from the aspectof liquid collection and leakage. The edge-parts 7, 8 can be folded andfixated in a number of ways within the scope of the following claims.

By constructing the inventive article from materials other than thoseconventionally used, it is not only possible to obtain athree-dimensional article by folding up the edge-parts of the articlealong said fold lines, but also to obtain considerably improvedliquid-retention and a drier abutment surface against the wearer's skinthan in the case of traditionally constructed absorbent pads in whichthe absorption material is mainly cellulose fluff. The fibres ofcellulose fluff normally have the drawback of discharging absorbedliquid when subjected to pressure, causing the surface material closestto the wearer's body to become moist or wet, and therewith resulting inincreased discomfort for the wearer. As a result of placing fibrewadding immediately beneath the liquid-impermeable surface material, thearticle will obtain a dry surface while, at the same time, the waddingwill provide a soft and comfortable layer of material against thewearer's skin. The structure of the fibre wadding includes very coarsecapillaries in comparison with the cellulose fluff, and consequentlyliquid will be transported very rapidly in the fibre wadding.

Furthermore, the fibre wadding alienates the liquid absorbed in theabsorbent pad from the body of the wearer, wherein the surface of theabsorbent article will be felt to be dry and comfortable, even when thearticle has been in use for some time. The fibre wadding alsocontributes towards configuring the article.

By choosing suitable material, it is possible to produce in thevoluminous bulky wadding layer a durable bond between surface material,fibre wadding and absorbent pad, or, as seen from the side of thearticle remote from the wearer, between surface material,plastic-barrier layer and absorbent pad, e.g. by gluing or welding.Because the fibre wadding comprises thermoplastic fibres and is alsohighly voluminous, the application of joins or seams therein will formin the bulky wadding deep, distinctive fold lines, outside of which theedge-parts of the article are folded-up so as to dam-in the central partof the article located between said edge-parts, said edge-parts beingfixated in their upwardly raised positions in relation to said centralpart.

Attached to the underside 25 of the article is an adhesive layer orstrip 18, by means of which the article can be removably fastened to theuser's underclothes when wearing said article Prior to use, thisadhesive layer 18 is protected by a protective strip 19, which ispreferably treated with a release agent on the side thereof facing theadhesive layer 18 and which can be readily removed when the article 1 isto be worn, so as to expose the adhesive layer 18 for active use.

FIG. 3 illustrates another embodiment of an absorbent article, herereferenced 1'. Similarly to the article 1, the article 1' incorporates aliquid-permeable sheet 2, which is located nearest the wearer, twolongitudinally extending fold lines 3, a central part 6, two edge-parts7, 8, and end-seals 5 which seal-off the end-parts 9', 10' of saidarticle. The rear end-part 9' is much larger than the front end-part10', so as to be able to receive faeces. Because of its enlargedend-part 9', the article 1' is able to enclose a larger absorbent padthan the article 1 of the embodiment before described, thereby enablingthe article 1' to absorb much larger quantities of liquid than those forwhich the article 1 is intended, for instance adult incontinence.

A number of modifications are conceivable within the scope of theclaims.

For instance, fold lines may also be provided on the underside of thearticle, with the intention of further amplifying the fold linesproduced on the upper side thereof. Naturally, a layer of fibre waddingcan also be positioned between the absorbent pad and theliquid-impermeable sheet in this case. Thus, all of the materialincorporated in the article can be joined together along the fold linesin conjunction therewith.

The methods by which the fold lines, for instance, seaming, glueing,welding, can also be combined. For instance, the liquid-permeable sheetcan be welded to the fibre wadding while glueing the wadding to theabsorbent pad along the fold lines are formed.

In addition to the absorbent pad described with reference to theillustrated exemplifying embodiments, a number of other absorbent padconstructions known to the person skilled in this art may beincorporated in the inventive article. For instance, the absorbent paddescribed with reference to FIG. 2 may be supplemented with a number oflayers of tissue or the like placed on one or both sides of theabsorbent body. It is also possible to use an absorbent pad made ofcellulose fluff, optionally with superabsorbents mixed therein. Theabsorbent pad may also have admixed therein material which has noabsorbing function, but which serves to improve binding to thesurrounding thermoplastic sheets. Such material may, for instance,comprise melt fibres. As will be understood, the fibre wadding may betotally excluded if so desired, in which case the article will solelyinclude an absorbent body comprising cellulose fluff, with or withoutsuperabsorbents or other absorbent material.

We claim:
 1. A disposable absorbent article, such as a diaper, anincontinence guard or the like, comprising an inner, liquid-permeablecasing sheet, which when the article is worn lies nearest the body ofthe wearer, an outer, liquid-impermeable casing sheet, an absorbent padenclosed between the inner and outer casing sheets, and a layer of fibrewadding disposed between the absorbent pad and the inner casing sheet,the inner casing sheet being joined to the absorbent pad along twolongitudinal lines forming permanent fold lines which divide thearticle, over at least a part thereof, into a central elongated part andtwo edge-parts located symmetrically on respective sides of the centralelongated part, and each edge-part being folded between the respectivefold line and its lateral edge such as to form a longitudinal fold inthe outer casing sheet, said fold being upstanding in a direction towardthe body of the wearer, said article having mutually opposed portions insaid longitudinal folds, which portions are permanently joined to eachother, whereby the edge-parts form inwardly upstanding embankment walls.2. An article (1, 1') according to claim 1, wherein the fibres of thefibre wadding (11) are from a group consisting of polyester,polypropylene, polyethylene fibres and mixtures thereof.
 3. An article(1, 1') according to claim 1, wherein the fold lines (3) comprise seamwelds.
 4. An article (1, 1') according to claim 1, wherein the foldlines (3) comprise adhesive bonds.